DE10305093A1 - Method and device for determining and monitoring contamination states of different liquids - Google Patents

Abstract

The invention relates to a method for determining and/or monitoring impurity states in different fluids by using crystalline inorganic semi-conductor diodes (LED) emitting a white light and injection light-emitting diodes emitting at least one infrared radiation (IRED) and/or ultra violet radiation (UVED). Said method uses, in particular, the modification of the emission spectrum of the white LED. Variations in the peak wave lengths, in the ratios of the peaks of the light-emitting injection in relation to the peak of the photoluminescence, in selective absorptions, in excitations on the fluorescence, in intensities of the peak wave lengths and in integral emissions are used in addition to comparison of data to the modified spectrum of the infrared emitter and/or the UV emitter. Said variations are registered with the help of a fibre optic compact spectrometer or a similar receiver. Said method is automatically calibrated if the ratio of the injection luminescence to the photoluminescence of the white LED for similar flowing current densities represents a diode specific constant. Exceptionally reliable economical sensors are produced and constructed in a fast manner according to said method and can be used in many methods associated with fluids, for example, in cleaning processes and chemical technology.

Description

The invention relates to a method for in-situ determination and monitoring of contamination states of liquids and / or or additionally to control liquid levels, this is the modification of the emission spectrum of a white light emitting diode when radiating liquids especially in comparison with the impurities present in them with the spectra of an IRED or a UVED and for the determination of changes in concentration of impurities and changes the types of contamination in liquids as well as variations in fluid levels in risers or in a bypass.

With the development of light emitting diodes (LED) based on a GaInN chip made it possible for the first time to create efficient, to produce blue light emitting diodes, which was in the early 90s Years demonstrated by Nakamura in the Japanese company NICHIA was [1]. Based on this development it was now possible to relatively old idea of excitation of phosphorescent layers on the pn junction to realize that in the 70s for the reverse process of multi-stage conversion of infrared radiation by luminophores on pn junctions from GaAs diodes produce visible light, but with very small external quantum yields was connected because it was an anti-Stokes process.

Such a diode that both blue light of the injection luminescence as well as a broad photoluminescence spectrum uses that by stimulating a certain proportion of the blue and consequently shorter-wave light is generated by both Nakamura in the company NICHIA [1] as well as employees of the Freiburg Fraunhofer Institute [2] proposed. Corresponding patents too white LEDs are available [3], [4].

Meanwhile, such LEDs have a high Production level reached and are in very large numbers distributed by several manufacturers (NICHIA, GOSEY, OSRAM, AGILENT et al.). Such LEDs have had the properties for a long time manufactured LED, d. that is, they have a very long service life on (to over 100,000 h) are also in the low microsecond range at high river currents controllable (modulation up to the high MHz range possible even with large river currents), show a direct proportionality between flux current density and number of emitted photons over several orders of magnitude of the river current a good coupling of the radiation into optical fibers (LWL) and are very inexpensive to acquire.

The infrared that can be used Radiation-emitting luminescent diode based on GaAlAs should be a peak wavelength have between 800 and 900 nm. Special claims up to a small beam angle is not set. Another usable emitter diodes with a peak wavelength around 370 nm can be used if statements on light scattering should be taken into account. Therefore a GaInN-UVED is used in the present invention, there at present no other UV emitters based on pn junctions in Semiconductors stand. The advantage of such a UVED is on the one hand that conventional Bypass and riser materials such as glass or plastic around 370 nm just enough are transparent and secondly in that a comparison with the often used Hg line at 365 nm becomes possible.

The basic structure of a white LED is in 1 shown schematically according to [5]. By the in a GaInN chip 1 located pn junction 2 a flow current is drawn, which leads to light emission in and in the immediate vicinity of the pn junction due to the radiative recombination of the injected electrons and holes. The blue light is emitted isotropically into the room, from which, however, only centered beams can be directed in a desired direction. The chip is made with an epoxy resin 3 sealed, in which organic or inorganic phosphors 4 are embedded. The electrodes act as carriers and for supplying the voltage 5 with an integrated calotte 6 , Finally, a thin bond wire ensures a closed circuit 11 , which has hardly any influence on the light emission due to its small diameter (shading negligible).

The chip is used to achieve high external quantum yields 1 in the mirrored calotte 6 a, which, as a concave mirror, reflects a large part of the lateral and rearward radiation towards the front and a fixed part of one of the electrodes 5 is. The injection luminescence thus has a directional characteristic, which is due to the lenticular plastic dome 7 bundled even further and can reach beam angles of a few degrees up to 180 ° (in SMD components).

This radiation pattern is hardly achieved by a phosphorescent layer 4 made from a mixture of organic or inorganic dyes with epoxy resin 6 exists and covers the calotte, changed. By absorbing part of the primary blue light of the injection luminescence in the dye 4 becomes a photoluminescence 8th . 10 caused, which is isotropic emitted into the room again. Due to the lens-like plastic dome, the formation of the photoluminescence is only possible incompletely, so that only rays 8th be bundled and can leave the lens dome towards the front. Compared to injection luminescence 9 the photoluminescence will have a slightly different directional characteristic due to the different locations of the light. Both types of light, ie the blue injection luminescence and the long-wave Photoluminescence is perceived jointly by the observer's eye, so that as a result of the additive color mixing, a more or less white light is observed, which, depending on the blue component, can have color temperatures between 5,000 K and 20,000 K.

In 2 a typical emission spectrum of such an LED can be seen. We see a short-wave blue band 12 , which corresponds to the injection luminescence, and a longer-wave wider band 13 belonging to the photoluminescence of the phosphor.

The change in the bands with the flow current is in 3 shown. If the sensitivity of the receiver is constant or kept constant, one can see that the curve 14 for 1 mA and the curve 15 are not fully developed for 5 mA. If you use a more sensitive detection area, you can use the curve 16 to 10 mA and with the curve 17 realize the state almost equal to 30 mA. When using the white LED, however, you must note that a slight peak shift can be observed with increasing flow current. However, since a selected flow current is mostly used for a sensor setting, this does not matter.

Due to the slightly different origins of the two types of light, a color change must occur at different viewing angles, ie the color coordinates change with the viewing angle. Since the radiation intensity is greatest in the zenith or straight direction, this effect can only be noticed with targeted observation. For selected viewing angles of 0 ° (curve 19 ), 10 ° (curve 20 ) and 40 ° (curve 18 ) you can see the spectral changes 4 remove. The spectra were normalized to the blue peak of the injection luminescence.

Through several publications ( DE 43 36 520 A1 . DE 195 24 326 A1 . DE 198 06 560 A1 . DE 198 57 845 A1 ) Devices and methods are already known by means of which light emitter diodes are used to determine the type and extent or level of such liquids, especially in washing liquids for washing machines or dishwashers. Methods are already known to compensate for the temperature drift of the diode parameters. These devices are designed according to the conditions of light emitting diodes described above.

The aim of the present invention is the evaluation accuracy of such methods and devices improve and simplify.

According to the invention, this is the goal achieved the changes of the emission spectrum to which the peak intensities are integral intensities of the entire spectrum and the supplemented individual spectra the injection luminescence and the photoluminescence that changed Increases in the flanks of the bands, the ratios of the peak wavelengths and of the integral intensities of the individual spectra, the shift of the peak wavelengths, contamination-specific Absorption and selective excitation of contaminants for fluorescence belong, be evaluated. According to the invention, the spectra are included of measurable changes with a fiber optic compact spectrometer or with a similar one opto-electronic receiver detected by means of optical fibers, the control of the Measurement procedure, storage and processing as well as evaluation is done with a computer.

In the invention presented here in contrast to the known measurement methods, it is always a limited one Angle of the radiation pattern used, so that the occurring Errors do not complicate the use of such a sensor, especially since the starting dates of the white ones LED after passing through distilled water or tap water always saved and later be used for standardization.

The proportionality of the intensity of the primary injection luminescence to the intensity of the secondary photoluminescence is of decisive importance for the ending. It should be sufficiently accurate in the usual operating range of the LED, i.e. in the range of the flux currents from about 0.1 mA to 100 mA (see also 3 for a smaller flow current range). Assuming this direct proportionality in a selected flow current range, the intensities of the peak wavelengths, the integral intensities of both bands and the half-widths of the two emissions change in the same way, i.e. one can consider the ratios of both bands as constant without a modifying medium. As noted above, this can always be saved as a base value at the beginning of the measurement procedure.

Another problem with the use of such a sensor arises due to the temperature dependence of the electrical parameters of semiconductor components. Assuming that work is carried out under constant current conditions, then for a flow current of about 5 mA there results a temperature coefficient of the flow voltage U _f of about 2.2 mV / K for the temperature-dependent flow voltage variation. Assuming, for example, that a washing machine is used in a temperature range of 5 ° C to 80 ° C, if the white and other LEDs also assume this temperature, the forward voltage would change by approximately 165 mV with a constant flow current.

This value can be easily coped with by a constant current feed, so that when a suitable supply source is used, the temperature dependence of the characteristic curves cannot have a major influence on the functioning of the sensor. This temperature dependency also results in a particular advantage of using such semiconductor emitters. Assuming the above temperature coefficient of the forward voltage at a constant flow current I _f as known, then a control unit can be used the temperature of the LED can be entered immediately to compensate for forward voltage. This gives you the opportunity to gain additional temperature influences and use them immediately to correct the temperature-dependent parameters.

However, attention must also be paid to that also the recombination properties of semiconductor injection diodes due to the temperature dependent bandgap have a temperature response. The shift in the peak wavelength from GaInN-LED generally has a temperature coefficient of about 0.06 nm / K (see [1]), while GaAlAs-IRED a larger value of about 0.12 nm / K. When used in the above temperature range would for the blue band of white LED a peak wavelength shift of maximum 4.5 nm. If you take room temperature of 22 ° C as a starting value, would Peak wavelength the white one LED and the UVED up to 80 ° C change by a maximum of 3.5 nm, what in the resolution area of fiber optic cheap compact spectrometer. For the IRED would result a value of about 9 nm.

Because the infrared band is very wide and their spectrum is only ever used as a comparison, the peak shift is of minor importance. The deviation the peaks with the temperature should, however, exceptionally evaluating the through the liquid with their contaminants modified radiation considered be what is indicated by the temperature from the above Forward voltage change immediately possible is.

The invention now relates to use such white ones LED, supplemented by UVED and / or IRED, for which Detection of contamination states and the change the same in liquids such that the LED on a bypass or on a riser or flow tube, in which a stationary column of liquid or a flowing liquid is present, be attached to their radiations after passage through the liquid from a glass or plastic light waveguide to a fiber optic Compact spectrometer or in a similar optoelectronic To be transferred to the recipient and the modification of the transmitted or scattered light is analyzed, with at least one LED in a straight line and in the 90 ° direction be attached and the light or radiation signals simultaneously or successively to a spectrometer or similar optoelectronic receiver are given. Depending on the switching state, an evaluation of the light or radiation emitting Diodes in dependence made from the state of contamination of the liquid.

Using several in the drawing illustrated embodiments the ending is explained below. show in the drawing

1 a schematic representation of the structure of a white LED,

2 typical emission spectra of a white NICHIA LED,

3 the current density dependence of the spectra of a white LED,

4 the angle dependence of the emission spectra of a white LED,

5 an arrangement of the LED in a first embodiment,

6 an arrangement of the light- or radiation-emitting diodes in a second embodiment,

7 the modification of the spectra of a white LED with different water densities,

8th dei modification of the transmission mission spectra of a white LED by washing processes in a test washing machine,

9 modification of the spectra of a white and an infrared diode,

10 the modification of the spectra of a white and an infrared diode with deliberate water pollution,

11 Scatter spectra (90 ° direction) of a white and an infrared emitter diode,

12 a transmission spectrum of normal tap water using a white LED and an ultraviolet light emitting diode (UVED) and

13 a transmission spectrum of river water (north German river at low tide) using a white LED and an ultraviolet light-emitting diode (UVED).

In the first embodiment 5 become the white LED 21 . 22 on a cylindrical bypass or riser 24 , which is blackened except for the light passage points 25 and thus greatly reduces reflections, by an offset angle of 90 °, whose weakly divergent rays through transparent windows 29 can penetrate into the liquid, there with the liquid 26 and / or can interact with the impurities and after passing through the window 29 in the optical fiber 23 penetrate, which transfers the measurement signal in a spectrometer or in a similar optoelectronic receiver.

That from the LED 21 outgoing light 27 is weakened by absorption and scattering. Since it is slightly divergent, the beams are also spread apart. Only a fraction of that from the LED gets into the receiver fiber 21 outgoing radiation. The measurable transmitted radiation will change more or less strongly with the type of liquid and depending on its impurities and their concentration. If contaminants are present in a liquid, the light can be scattered and selectively absorbed on them, in some cases even causing the contaminants to fluoresce can lead.

Such fluorescence then shows up as spectral changes in the long-wave shoulders of the bands. The scattering of light or radiation now depends on the size of the scattering centers, on their symmetry, their refractive index and on their concentration. If the scattering centers are significantly smaller than the wavelength of the scattered radiation, then the scattering intensity can be described by the Rayleigh theory, which has a symmetrical cos-like intensity distribution with values between 1 and 2, whereby polarization effects will not be discussed here. their intensity is inversely proportional to a constant angle setting of the wavelength (I (λ) = const. λ ^–n ), the exponent n having a value of approximately 4.2.

In order to be able to differentiate the scattered radiation from the direct radiation as well as possible, measurements are often taken in the 90 ° direction. Since LEDs are very cheap and can be easily switched on and off electronically, a second white LED is used instead of the optical waveguide required in the 90 ° direction 22 attached whose radiation 28 not directly into the optical fiber 23 can get there, but from the black wall 25 is absorbed. This also has the advantage that no multiplexer is required for the optical fibers to the spectrometer. The scattered rays 30 partially get into the optical fiber 23 and are sent to the recipient.

The simple switching on and off of the LED 21 and 22 now allows both the direct transmitted light modified by the liquid and the scattered light to be measured 30 the LED 22 to register in the 90 ° direction. So you can separate scattering and absorption influences by the medium liquid and also detect when switching on both LEDs at the same time. The latter case is an additive control measurement and is used to compare the signals of the individually switched on LED.

The scattering centers get bigger and bigger and their diameter gradually increases comparable to the wavelength the primary radiation or even bigger than same, then the intensity distribution can be described by the Mie theory. This mathematically demanding Contains theory only the refractive indices of the medium and the Scattering centers, the size of the scattering centers and their symmetry and represents the general solution to the combined diffraction and absorption problem of contaminants in media with a refractive index that is from which the impurities must differ. The result receives one through series developments of complicated functions, whereby the Rows converge poorly and therefore a very large number considered by limbs must be what is not in the age of fast computers restriction represents more.

With increasing particle size, an ever greater intensity of the scattered radiation in the forward direction is obtained with a simultaneous weak dependence on the wavelength of the radiation used, which is then in accordance with 5 an increase in direct radiation 27 means. In the event of a corresponding contamination, one can therefore compare both types of scatter and make appropriate conclusions with regard to the scatter centers and their size and concentration when using the method 5 pull. If the type or concentration of impurities changes, then there is the basic possibility of dividing the spectra of the forward direction of different states by one another, so that the changes in the scattering and absorption influences can be made visible.

In 7 is a spectral modification of a white LED through different waters. During the curve 43 contains the LED spectrum for tap water, represents the curve 42 River water at a low water level in a north German river (at low tide). The curve 41 , measured on slightly polluted water, entails both a sharp decrease in the short-wave peak and a shift in the peak wavelength of the long-wave band.

These measured principal behaviors occur repeatedly with liquids that are not extremely heavily contaminated. Too high a concentration of impurities, however, leads to such high ones Absorptions that no longer pass direct or scattered light leave and consequently no longer allow measurement.

In 8th Four spectra of a white LED are shown, which were recorded on deliberately contaminated water. The spectrum of the curve 47 corresponds to that of normal power water (Berlin water: hardness about 18 ° dH). The peak wavelengths and the relative intensity units are as parameters in 8th included. The curves 46 and 45 stiff impurities of dirt in water, whereby the dirt dissolved in water after different solution times from test fabrics from EMPA (St. Gallen). The spectrum 44 was out 45 won by adding red wine to the slightly polluted water.

• (i) eine Peakwellenlängenverschiebung des blauen Peaks,
• (ii) eine Verschiebung der maximalen Peakwellenlänge der langwelligeren Bande,
• (iii) eine unterschiedliche Abnahme der Intensitäten,
• (iv) veränderte Anstiege der kurzwelligen Flanken beider Banden, und
• (v) dass die Flächen der einzelnen Spektren sowie die Flächenverhältnisse der rekonstruierten Einzelspektren (rekonstruierte gaußähnliche Kurven unter Berücksichtigung der Schiefe) unterschiedlich sind.

One recognises

• (i) a peak wavelength shift of the blue peak,
• (ii) a shift in the maximum peak wavelength of the longer wavelength band,
• (iii) a different decrease in intensities,
• (iv) changed increases in the short-wave flanks of both bands, and
• (v) that the areas of the individual spectra as well as the area ratios of the reconstructed individual spec tren (reconstructed Gaussian curves taking skewness into account) are different.

For example, the peak ratios change between the long-wave band for the blue emission of the curves 47 to 44 from 2.10 to 2.48 and 2.83 to 3.30, which, after appropriate calibration, represents very good threshold values for in-situ optimization of processes. Similar relationships also occur for the other parameters mentioned.

The second embodiment according to 6 now also uses white LEDs and also infrared emitters, which for example emit infrared radiation with a peak wavelength of around 860 nm, and optionally also UVED with a peak wavelength around 370 nm 6 are at the bypass 24 with a corresponding blackening 25 one white LED each 31 respectively. 33 attached as in the example above, through the window 29 a measurement of the transmitted light 35 and the scattered light 39 of the primary beam 37 by means of an optical fiber 23 (LWL) and a recipient is possible. Different switching states of the two diodes can be used to measure transmission and scatter as above. At the positions 32 and 34 IRED or optionally UVED can now be attached, whereby a combination of both is also possible at these positions. You can see the rays 36 respectively. 37 send out. Your radiation can go straight from the position 32 and as scattered radiation from the scattering centers 40 out, caused out of position 34 , are registered.

The following measurement sequences are now optionally possible:
Analogous to the first example, all measurement types are included as discussed above. If you add the IRED to the white LED, the infrared (IR) spectra can always be measured as a control, which is the case when the IR spectrum of the IRED is hardly changed 34 but greatly changed spectrum of the white LED 33 allows clear statements about radiation scattering. If the light absorption and control is already very high, you also gain from the data of the white LED 31 and the I-RED 32 still statements on forward scatter and the wavelength-dependent absorption, which is clearly different from the short-wave due to the different impurities in the infrared. If you place the IRED on the positions 32 and 33 UVED, then effective short-wave absorptions and especially the very effective Rayleigh scattering in short-wave can be detected well. A combination of one IRED and one UVED ultimately opens up all detectable absorptions and scattering in the straight direction and in the 90 ° direction. Since all LEDs, IRED and UVED can be quickly switched according to the program in synchronization with the spectrometer from the computer, which is not shown in the drawing, the measurement can be carried out in all links with short integration times in about one second. The cost compared to the first embodiment is negligible (a few euros), which the latter variant recommends as a universal sensor.

Another embodiment based on 5 and 6 can be seen in the following figures. 9 contains measurement results of Berlin tap water contaminated with red wine. The value of the maximum for tap water, not shown, is approximately 1629 relative units (r.E.) for the peak at 458.4 nm, while it is approximately 3391 r for the peak of photoluminescence at 549.4 nm. E. is. Decisive changes occur when adding red wine. The curve 51 corresponds to the transmission through a mix of tap water and red wine of 6: 1, while the following curves 50 . 49 and 48 at ratios of 5: 1, 3: 1 and 2: 1. The peak wavelength of the blue band does not shift with the red wine concentration compared to the tap water value (458.4 nm), although its intensity also decreases significantly. The long-wave band behaves differently, which is both influenced in intensity and exhibits a peak shift. The values are given below.

You can see the smaller one very well Transmission in red and the stronger one in the blue. In this case we are more selective absorption because to do with scatter effects. The differences in value are very large; so sensors can be addressed well.

The peak shift in the area of the long-wave band is between the curves 51 and 48 about 60 nm, which is a very detectable signal for a sensor. If we then look at the areas of the short-wave band from the short-wave limit to the minimum (around 490 nm) (A _b1 to A _b4 ) and the long-wave band from 490 nm to the near infrared (A _g1 to A _g4 ) then rate you get the following values:
A _g1 : A _b1 = 9.9
A _g2 : A _b2 = 11.2
A _g3 : A _b3 = 15.6
A _g4 : A _b4 = 21.6

Also the rises of the long wave band of curves 48 to 51 can be used to track the concentration and type of contamination. At 517 nm, for example, they change as follows:
Curve ( 51 ): 2.5
Curve ( 50 ): 1.6
Curve ( 49 ): 0.9
Curve ( 48 ): 0.5

As you can easily see, remains the long-wave part of the photoluminescence band of about 650 nm almost unadulterated constant.

So there are the peak shifts, the rises of the gangs, the area ratios, the intensity ratios, the half-widths (as far as recognizable or identifiable) and selective absorptions and emissions for pollution sensors to disposal.

Another support of the mentioned embodiments is by 10 given. The curve with the maxima 52 . 53 and 54 originate from the emissions of a white LED and an IRED and were recorded on tap water containing red wine. From the changes in the spectra, here occurs in the gang 53 hardly any absorption or scattering can be deduced from the contamination or the degree of "pollution".

The spread spectra also bring this in 11 to expression. They were taken up in water containing milk. The intensities of the 90 ° scatter are shown in r. E. While the spectrum of the white LED with the maxima 55 and 57 strongly modified, join in the IR band 54 . 56 and 59 no significant structural changes. Of course, the white LED can 58 no longer produce scatter. In this case we are dealing with the almost wavelength-independent Mie scattering. From the changes in the spectra in relation to "pure" tap water, clear statements can be made about the degree and type of "pollution".

Another application example is by 12 and 13 illustrated. Here a white LED and a UVED were in the positions 31 and 32 the 6 used. The spectra of the diodes after their radiation has passed through normal tap water are in 12 shown. The peaks of the UVED are clearly visible 60 and the white LED 61 and 62 , The peaks at 63 and 64 represent the 2nd order of the UV emission at 375 nm and the blue band at about 470 nm, which are also recorded by the spectrometer after passing through the liquid. They can also be used for evaluation. Now consider the structural changes in river water according to 13 , then a strong reduction of the short-wave bands and consequently the respective 2nd order of both bands is found. This does not require comparisons of the absolute values of the spectra, which for this reason were not recorded. The advantage arises from the fact that with only a slightly changed sensitivity of the spectrometer or the fiber optic connecting elements there is no need for absolute measurements. That is precisely the great advantage of the present invention.

If one designates the intensities of the maxima of the individual bands with I ₁ to I ₅ starting from the short-wave, the following data are obtained for tap water or for river water.

From the comparison of the table of values above, it can be seen that the second-order data for the UVED provide almost the same values, but that the value for river water is weakened due to the scatter in the UV compared to normal water. With the 2nd order of the blue band there is only a very slight deviation in the 2nd order compared to normal water, which indicates a weak scattering effect in the blue, but can also be partly due to measurement errors. As already indicated above, the 2nd order of the UVED and the blue band of the white LED can help to quickly identify the effects of scattering. In addition, the differences between the different waters are relatively large in almost all circumstances, so that with appropriate calibrations, clear threshold values are available for process optimizations and controls as well as monitoring.

references

• [1] S. Nakamura and G. Fasol: "The Blue Laser Diode", Springer-Verlag, Berlin 1997.
• [2] P. Schlotter, R. Schmidt and J. Schneider: "Luminescence or blue light emitting diodes ", Appl. Phys. A64 (1997), pg. 417-418.
• [3] DE 196 25 622 A1 , OT: January 2, 1998; U. Reeh et al .: "Light-emitting semiconductor component with luminescence conversion element".
• [4] DE 196 38 677 A1 , OT: April 2, 1998; P. Schlotter et al .: "Mixed-color light-emitting semiconductor component with luminescence conversion element".
• [5] J. Baur, P. Schlotter and J. Schneider: "White light emitting diode", solid state problems 37: 67-78 (1998).

Claims (18)

Methods for in-situ determination and monitoring of contamination states of liquids and / or or additionally to control liquid levels with white Light emitting diodes and in addition also with infrared or ultraviolet radiation emitting semiconductor injection diodes and a fiber optic spectrometer or the like optoelectronic receiver on a riser or flow tube or on a bypass whose Spectra modification by the liquid and / or by the consciously or unconsciously into the liquid introduced impurities in different positions and switching states be evaluated. A method according to claim 1, characterized in that that one of a white LED generated radiation in the bypass or the riser or flow tube offset by 90 ° is irradiated to both the transmission and the scatter spectra in 90 ° direction to be able to measure. A method according to claim 2, characterized in that that for better detection of the wavelength-dependent radiation scatter in parallel to that by the white LED still radiated radiation from an ultraviolet diode (UVED) , which then leads to an even clearer scatter detection, because the scattering intensity quickly with decreasing wavelength increases. A method according to claim 2 or 3, characterized in that another parallel to the one generated by the white LED Radiation of an IRED is irradiated, so that the wavelength-dependent absorption and Scattering processes due to contamination can be interpreted more clearly become. A method according to claim 3 or 4, characterized in that the forward voltage at a constant flow current the white one LED or the other IRED or UVED used and related to each other and a temperature specification is obtained and changes in forward voltage to correct the temperature-dependent Spectra shift over a control element can be used. Method according to one of claims 3 to 5, characterized in that alternating with the radiations of the white LED one radiation each from a UVED and an IRED is irradiated in order to both scattering and absorption processes for control and regulation ready to provide. Method according to one of the preceding claims, characterized in that by the liquid Radiated and modified with their impurities over a Fiber optic or fiber optic the fiber optic compact spectrometer or similar optoelectronic receiver fed for evaluation becomes. A method according to claim 8, characterized in that that the forward voltages for the LED, UVED and IRED are pulsed so that radiation changes due to surface changes in the measuring containers can be perceived. Method according to one of the preceding claims, characterized by modulating the forward voltages of the LED, UVED and IRED to be different with selectively sensitive amplifiers and / or receivers To be able to distinguish groups of emitters. Method according to one of the preceding claims, characterized in that the peaks, the peak shifts, the integral intensities, the peak ratios to each other, the changed Increases in all flanks of the bands, the integral intensities of the blue spectrum of the injection luminescence and the spectrum of the Photoluminescence of the Gaussian curves and the half widths from the spectrometer data in situ with a fast PC can be evaluated, which also optimizes and / or The ongoing process is controlled. A method according to claim 12, characterized in that that the respective 2nd order of each spectrum for evaluation and especially for intensity comparison is used. A method according to claim 13, characterized in that that the spectra change in the forward direction, for example of the fluid state (Change the impurities and their concentrations) divided by each other or subtracted so that the scatter and absorption changes better can be made visible. Device for performing the method according to a of claims 1 to 12, characterized in that at least two white LEDs on Bypass or riser or flow tube offset by 90 ° to each other are attached. Device according to claim 13, characterized in that that parallel to the white ones LED is still an ultraviolet diode (UVED) attached. Device according to claim 13 or 14, characterized in that an IRED is attached in parallel to the white LED is. Device according to claim 14 or 15, characterized in that one alternates parallel to the white LED UVED and an IRED are attached. Device according to one of claims 13 to 16, characterized in that that for each radiation emitter on the bypass or on the riser or flow tube a transparent area is provided by a blackened area on the container is surrounded. Device according to one of claims 13 to 16, characterized in that that at least some of the radiation emitters are removed from the measuring container arranged and over Optical fibers made of quartz, glass or plastic (POF) with the coupling steles on the measuring container is optically coupled.